Structure of low-profile heat pipe

ABSTRACT

A structure of low-profile heat pipe includes a flat heat-transfer pipe head and an elongated flat flow-guide pipe body formed in integrity, a heat-transfer cover plate affixed to the flat heat-transfer pipe head and the elongated flat flow-guide pipe body, a cavity defined in between the flat heat-transfer pipe head and elongated flat flow-guide pipe body and the heat-transfer cover plate and holding a working fluid and defining a condensation side at its one end remote from the flat heat-transfer pipe head and an evaporation side at its other end within the flat heat-transfer pipe head, and a wick structure surrounding and in communication with the cavity.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to heat sink technology and more particularly, to a structure of low-profile heat pipe that simplifies the fabrication and enhances the heat dissipation efficiency.

2. Description of the Related Art

A heat pipe design is known comprising a heat-transfer pipe head and a heat pipe body. The heat-transfer pipe head defines therein a recessed hole. The heat pipe body has its one end embedded in the recessed hole of the heat-transfer pipe head. During application of the heat sink, the heat-transfer pipe head is attached to the surface of an electronic component to absorb waste heat. When the heat-transfer pipe head absorbs heat energy from the electronic component, it heats the heat pipe body, causing vaporization of a fluid at one end of the heat pipe body and release of heat energy at the other end of the heat pipe body by condensation of the vapor. However, the heat pipe body and heat-transfer pipe head of this design of heat pipe must be separately made and then joined together. In consequence, the fabrication of this design of heat pipe requires much labor and time and can cause a defective product problem. Following the market trend of the electronic industry toward a low profile design, the vertical installation space in an electronic device for heat pipe must be minimized. Further, it is the market trend to create electronic products having a low profile. In consequence, the vertical installation space in an electronic device for heat pipe must be minimized. However, according to the aforesaid prior art heat pipe design, the heat pipe body has its one end embedded in the recessed hole of the heat-transfer pipe head. This design does not allow significant reduction of the vertical thickness of the heat pipe, restricting the range of applications. Further, if the bonding tightness between the heat pipe body and the recessed hole of the heat-transfer pipe head is insufficient, the heat transfer efficiency will be affected, lowering the performance of the heat pipe. Further, more of the working fluid cannot be accommodated due to the limited volume of the heat pipe body, resulting in poor cooling effect.

SUMMARY OF THE INVENTION

The present invention has been accomplished under the circumstances in view. It is one object of the present invention to provide a structure of low-profile heat pipe, which simplifies the fabrication, increases the yield, and enhances the heat dissipation efficiency.

To achieve this and other objects of the present invention, a low-profile heat pipe comprises a flat heat-transfer pipe head, an elongated flat flow-guide pipe body formed integral with and extended from one side of the flat heat-transfer pipe head, an elongated recessed cavity located at the top wall of the flat heat-transfer pipe head and the top wall of the elongated flat flow-guide pipe body and extending along the length of the elongated flat flow-guide pipe body and defining a condensation side at its one end remote from the flat heat-transfer pipe head and an evaporation side at its other end within the flat heat-transfer pipe head, a heat-transfer cover plate fixedly fastened to the flat heat-transfer pipe head and the elongated flat flow-guide pipe body to keep the elongated recessed cavity airtight, a plurality of flow-guide grooves formed in the elongated recessed cavity, a working fluid sealed in the elongated recessed cavity, and a wick structure sintered on the flat heat-transfer pipe head and the elongated flat flow-guide pipe body within the elongated recessed cavity and the bottom wall of the heat-transfer cover plate corresponding to the elongated recessed cavity.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a structure of low-profile heat pipe in accordance with a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line C-C of FIG. 1.

FIG. 3 is an exploded view of the structure of low-profile heat pipe in accordance with the first embodiment of the present invention.

FIG. 4 is a schematic exploded view of the first embodiment of the present invention, illustrating an application status of the structure of low-profile heat pipe.

FIG. 5 is an exploded view of a structure of low-profile heat pipe in accordance with a second embodiment of the present invention.

FIG. 6 is an elevational view, partially cutaway of a structure of low-profile heat pipe in accordance with a third embodiment of the present invention.

FIG. 7 is a sectional view taken along line D-D of FIG. 6.

FIG. 8 is an exploded view of the structure of low-profile heat pipe in accordance with the third embodiment of the present invention.

FIG. 9 is a schematic drawing illustrating an application status of the structure of low-profile heat pipe in accordance with the third embodiment of the present invention.

FIG. 10 is an exploded view of a structure of low-profile heat pipe in accordance with a fourth embodiment of the present invention.

FIG. 11 is an exploded view of a structure of low-profile heat pipe in accordance with a fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 1-3, a structure of low-profile heat pipe 10 in accordance with a first embodiment of the present invention is shown. The structure of low-profile heat pipe 10 comprises a flat heat-transfer pipe head 1, an elongated flat flow-guide pipe body 2 formed integral with and extended from one side of the flat heat-transfer pipe head 1, an elongated recessed cavity 3 located at the top wall of the flat heat-transfer pipe head 1 and the top wall of the elongated flat flow-guide pipe body 2 and extending along the length of the elongated flat flow-guide pipe body 2, a plurality of flow-guide grooves 6 formed in the elongated recessed cavity 3, an endless groove 33 located at the flat heat-transfer pipe head 1 and the elongated flat flow-guide pipe body 2 in communication with and around the elongated recessed cavity 3, a heat-transfer cover plate 4 press-fitted into the endless groove 33 and fixedly fastened to the flat heat-transfer pipe head 1 and the elongated flat flow-guide pipe body 2 by welding to keep the elongated recessed cavity 3 airtight, a wick structure 5 sintered on the wall of the flat heat-transfer pipe head 1 and elongated flat flow-guide pipe body 2 within the elongated recessed cavity 3 and the bottom wall of the heat-transfer cover plate 4 corresponding to the elongated recessed cavity 3, and a working fluid 34 sealed in the elongated recessed cavity 3. Further, the elongated recessed cavity 3 defines a condensation side 31 at its one end remote from the flat heat-transfer pipe head 1 and an evaporation side 32 at its other end within the flat heat-transfer pipe head 1.

Referring to FIG. 4 and FIG. 3 again, during application of the structure of low-profile heat pipe 10, attach the bottom wall of the flat heat-transfer pipe head 1 to the surface of the electronic component A to be cooled, and then attach a heat sink B to the top wall of the heat-transfer cover plate 4 corresponding to the condensation side 31 of the elongated recessed cavity 3. During operation of the electronic component A, the flat heat-transfer pipe head 1 absorbs heat energy from the electronic component A and transfers absorbed heat energy to the working fluid 34 in the evaporation side 32 of the elongated recessed cavity 3, causing vaporization of the working fluid 34. The vapor condenses back into a liquid at the condensation side 31 of the elongated recessed cavity 3 and is absorbed by the wick structure 5, releasing the latent heat. The working fluid 34 then returns to the evaporation side 32 of the elongated recessed cavity 3, and evaporates at the evaporation side 32 once more and repeats the cycle.

In the aforesaid first embodiment of the present invention, as shown in FIG. 3, the condensation side 31 and evaporation side 32 of the elongated recessed cavity 3 are equal in width. In a second embodiment of the present invention, as shown in FIG. 5, the evaporation side 32′ of the elongated recessed cavity 3 has a relatively larger width than the condensation side 31 for accommodating a relatively larger amount of the working fluid 34 to enhance the heat transfer efficiency of the structure of low-profile heat pipe 10.

FIGS. 6-8 illustrate a structure of low-profile heat pipe 20 in accordance with a second embodiment of the present invention. According to this embodiment, the structure of low-profile heat pipe 20 comprises a flat base member 7 and a flat cover member 8. The flat base member 7 is a single piece member comprising an expanded head portion 71, a narrow elongated body portion 72 extended from a middle part of one side of the expanded head portion 71, a peripheral endless upright wall 73 extending around the expanded head portion 71 and the narrow elongated body portion 72, and an endless groove 74 located on the inner surface of the peripheral endless upright wall 73. The flat cover member 8 is press-fitted into the endless groove 74 and fixedly fastened to the flat base member 7 by welding. Thus, an enclosed cavity 9 is defined in between the flat base member 7 and the flat cover member 8. Further, a working fluid 93 is sealed in the enclosed cavity 9. Further, the enclosed cavity 9 defines an evaporation side 91 at its one end within the expanded head portion 71 of the flat base member 7, and a condensation side 92 at its other end within the narrow elongated body portion 72 of the flat base member 7 and remote from the expanded head portion 71. Further, a plurality of flow-guide grooves 6 are formed in the flat base member 7 within the enclosed cavity 9, and a wick structure 5′ is sintered on the flat base member 7 and the flat cover member 8 in communication with and around the enclosed cavity 9.

Referring to FIG. 9 and FIGS. 6-8 again, during application of the structure of low-profile heat pipe 20, attach the bottom wall of the expanded head portion 71 of the flat base member 7 to the surface of the electronic component A to be cooled, and then attach a heat sink B to the top wall of the heat-transfer cover member 8 corresponding to the condensation side 92 of the enclosed cavity 9. During operation of the electronic component A, the expanded head portion 71 of the flat base member 7 absorbs heat energy from the electronic component A and transfers absorbed heat energy to the working fluid 93 in the evaporation side 91 of the enclosed cavity 9, causing vaporization of the working fluid 93. The vapor condenses back into a liquid at the condensation side 92 of the enclosed cavity 9 and is absorbed by the wick structure 5′, releasing the latent heat. The working fluid 93 then returns to the evaporation side 91 of the enclosed cavity 9 through the wick structure 5′, and evaporates at the evaporation side 91 once more and repeats the cycle.

FIG. 10 illustrates a structure of low-profile heat pipe in accordance with a fourth embodiment of the present invention. This fourth embodiment is substantially similar to the aforesaid third embodiment with the exception that the flat base member 7 further comprises a transition portion 75 connected between the expanded head portion 71 and the narrow elongated body portion 72 and reducing in width gradually from the expanded head portion 71 toward the narrow elongated body portion 72 to enhance flowability of the working fluid 93.

FIG. 11 illustrates a structure of low-profile heat pipe in accordance with a fifth embodiment of the present invention. This fifth embodiment is substantially similar to the aforesaid fourth embodiment with the exception that the width of the transition portion, referenced by 76 is smoothly curved and reducing in direction from the expanded head portion 71 toward the narrow elongated body portion 72.

In conclusion, the invention provides a structure of low-profile heat pipe 10;20 that has the advantages and features as follows:

1. When the flat heat-transfer pipe head 1 of the structure of low-profile heat pipe 10 or the expanded head portion 71 of the flat base member 7 absorbs heat energy from the electronic component A, it directly transfers absorbed heat energy to the working fluid 34;93, causing vaporization of the working fluid 34;93.

2. The structure of low-profile heat pipe 10;20 can be configured subject to user's or designer's demand, having the characteristics of low thickness, ease of fabrication and low manufacturing cost.

3. The volume of the cavity 3;9 of the structure of low-profile heat pipe 10;20 can be determined subject to the designer's demand for accommodating a large amount of working fluid 34;93. 

What the invention claimed is:
 1. A structure of low-profile heat pipe, comprising: a flat heat-transfer pipe head; an elongated flat flow-guide pipe body formed integral with and extended from one side of said flat heat-transfer pipe head; an elongated recessed cavity located at a top wall of said flat heat-transfer pipe head and a top wall of said elongated flat flow-guide pipe body and extending along the length of said elongated flat flow-guide pipe body, said elongated recessed cavity defining a condensation side at one end thereof remote from said flat heat-transfer pipe head and an evaporation side at an opposite end thereof within said flat heat-transfer pipe head; and a heat-transfer cover plate fixedly fastened to said flat heat-transfer pipe head and said elongated flat flow-guide pipe body to keep said elongated recessed cavity airtight.
 2. The structure of low-profile heat pipe as claimed in claim 1, further comprising an endless groove located at said flat heat-transfer pipe head and said elongated flat flow-guide pipe body in communication with and around said elongated recessed cavity; said heat-transfer cover plate is press-fitted into said endless groove and peripherally bonded to said flat heat-transfer pipe head and said elongated flat flow-guide pipe body.
 3. The structure of low-profile heat pipe as claimed in claim 1, further comprising a wick structure sintered on said flat heat-transfer pipe head and said elongated flat flow-guide pipe body within said elongated recessed cavity and a bottom wall of said heat-transfer cover plate corresponding to said elongated recessed cavity.
 4. The structure of low-profile heat pipe as claimed in claim 1, further comprising a plurality of flow-guide grooves formed in said elongated recessed cavity.
 5. The structure of low-profile heat pipe as claimed in claim 1, further comprising a working fluid sealed in said elongated recessed cavity.
 6. A structure of low-profile heat pipe, comprising: a flat base member being a single piece member comprising an expanded head portion, a narrow elongated body portion extended from a middle part of one side of said expanded head portion and a peripheral endless upright wall extending around said expanded head portion and said narrow elongated body portion; a flat cover member fixedly fastened to said flat base member; and an enclosed cavity defined in between said flat base member and said flat cover member, said enclosed cavity defining an evaporation side at one end thereof within said expanded head portion of said base member and a condensation side at an opposite end thereof within said narrow elongated body portion of said flat base member and remote from said expanded head portion.
 7. The structure of low-profile heat pipe as claimed in claim 6, wherein said flat base member further comprises an endless groove located on an inner surface of said peripheral endless upright wall; said flat cover member is press-fitted into said endless groove and then fixedly fastened to said flat base member.
 8. The structure of low-profile heat pipe as claimed in claim 6, further comprising a wick structure sintered on said flat base member and said flat cover member in communication with and around said enclosed cavity.
 9. The structure of low-profile heat pipe as claimed in claim 6, further said flat base member further comprises a plurality of flow-guide grooves formed in said enclosed cavity.
 10. The structure of low-profile heat pipe as claimed in claim 6, further comprising a working fluid sealed in said enclosed cavity. 